Loss of Body Water Progressive Effects of Dehydration
0-1% Thirst
2-5% Dry mouth, flushed skin, fatigue, headache, impaired physical performance
6% Increased body temperature, rate of breathing and pulse rate; dizziness; weakness
8% Dizziness, increased weakness, labored breathing with exercise
10% Muscle spasms, swollen tongue, delirium
11% Poor blood circulation, failing kidney function

The American Dietetic Association's Complete Food & Nutrition Guide (Minneapolis: Chronimed Publishing; 1996), p.168

  • The National Research Council (NRC) uses a sliding scale of 1 milliliter of water for every calorie burned. The NRC says the average man — who burns about 2,900 calories daily — needs 2,900 milliliters, or about 12 cups, of water each day. The average woman — who burns 2,200 calories daily — needs about 2,200 milliliters, or about 9 cups, of water each day. For your own calculations: One measuring cup (8 ounces) of water equals 236 milliliters of water.
    Mayo Clinic, Consumer Health Tips and Products, June 25,2002.
  • The American College of Sports Medicine (ACSM) recommends drinking about 17 ounces of liquid 2 hours before exercise and drinking early and at regular intervals during exercise (5-8 oz every 15-20 minutes).
    “Exercise and Fluid Replacement,” ACSM, Vol.28, No.1, 1-1996.
  • Mild to severe dehydration commonly occurs among athletes, even when fluid is readily available. Consequently, it is in the athlete’s best interest to adopt fluid-replacement practices that promote fluid intake in proportion to sweat loss.
    Int J Sport Nutr 1995 Jun;5 Suppl:S62-73.
  • Increasing dehydration, due to inadequate fluid consumption, directly impairs stroke volume, cardiac output, and skin blood flow, which results in larger increases in body core temperature, heart rate, and ratings of the difficulty of exercise
    Med Sci Sports Exerc 1992 Sep;24 (9 Suppl):S324-30.
  • Hyponatremia (low blood sodium levels) as a result of over-hydration, has become more and more common in endurance athletes, and many governing bodies are changing their hydration recommendations accordingly. To prevent complications, endurance athletes are advised to be aware of the effect of dehydration as well as over-hydration and plan their fluid intake according to their individual needs.
    The Physician and SportsMedicine - Vol 31 - No. 7 - July 2003
  • The average American is chronically dehydrated and consumes only 4.6 servings of water per day. Survey of 3003 Americans, Nutrition Information Center, New York
    Hospital-Cornell Medical Center (April 14, 1998).
  • DRINK LOTS OF water and keep yourself on schedule” is an old health adage. Recent studies have demonstrated that drinking water is, indeed, associated with a substantial physiological response. Drinking 500 ml of water increased metabolic rate by 30%. The increase occurred within 10 min and reached a maximum after 30–40 min. The total thermogenic response was about 100 kJ (which equals about 96 kcal per day or a loss of 5.5 lbs per year).
    Journal of Clinical Endocrinology & Metabolism 88(12):6015–6019, 03'.
  • Dehydration is one of the ten most common causes for hospitalization among Medicare patients. In 1991, 6.7% (731,695) of Medicare hospitalizations had dehydration listed as a principal diagnosis, costing Medicare more than $446 million in hospital payments. Most importantly, the study revealed that about half of the people over age 65 who were hospitalized with illnesses accompanied by dehydration die within one year of admission.
    Am J Public Health 1994 Aug;84(8)1265-9.
  • Nursing facility residents are particularly at risk for dehydration. As many as 75% of residents have average fluid intakes below 1,500 cc per day, while a minimum recommendation is between 1,500 to 2,000 cc of fluid a day. These residents may need more opportunities and reminders to drink.
    Practical Solutions to Preventing Dehydration, Illinois Council on Long Term Care, 1997 Feb, 7 (#198).
  • New research indicates that fluid consumption in general and water consumption in particular can have an effect on the risk of urinary stone disease; cancers of the breast, colon, and urinary tract; childhood and adolescent obesity; mitral valve prolapse; salivary gland function; and overall health in the elderly. Dietitians should be encouraged to promote and monitor fluid and water intake among all of their clients and patients through education and to help them design a fluid intake plan.
    J Am Diet Assoc 1999 Feb;99(2):200-6.